Observation of an interfacial magnon-electron drag in a pyrochlore ferromagnet–heavy metal heterostructure

Abstract

We report on how the deposition of a nonmagnetic metal on the surface of a ferromagnetic insulator can provide a sensitive, albeit indirect, means of measuring the magnon Hall effect. This is inferred from the thermoelectric potential that develops across the metal layer as a consequence of the transverse thermal Hall gradient. Moreover, a manifestation of magnon surface states is observed via the drag which the surface spin currents of the ferromagnet impose on the conduction electrons of the adjacent metallic layer. This electron-magnon interaction operates across the interface, and the polarity of the resultant drag voltage is determined by the spin Nernst angle of the metal layer.